In patent application Ser. No. 212,902, filed Dec. 4, 1980, and now abandoned, there was shown and described a method and apparatus whereby strips of extruded rubber (or equivalent resilient, flexible material) were secured to a backing sheet and to each other. There was further described a method and apparatus whereby the interrelated strips, thus formed, were used to form a pattern which, in turn, was used for purposes including (among others) the orientation of further strips.
The last-mentioned method and apparatus have proved not commercially satisfactory, especially for the crucially-important large-diameter pads. Reasons for this include the fact that extrusions of rubber are not perfect but instead vary somewhat along their lengths.
Especially in large-diameter commercial apparatus intended to have a very large production rate, there must be many strips (called "leads") spiraling outwardly from the center. These leads must be closely spaced, and must touch each other for the apparatus to operate satisfactorily. Since the method whereby a pattern is employed to orient the leads has proved not commercially satisfactory, it has been a major problem to invent a method of manufacturing pads (especially large-diameter pads having many leads) in any practical and satisfactory manner.
The apparatus illustrated in the cited patent application has a flat bottom. However, round or upwardly-concave bottoms (and associated pads secured thereto) are known in the art. It is a major problem to effect mounting of a strip-formed ore-concentrating pad in an upwardly-concave bowl, again so that practical and satisfactory manufacturing of ore concentrators may be effected.